JSX stands for JavaScript XML, and it is a syntax extension for JavaScript that allows you to write HTML-like syntax directly in your JavaScript code. It’s used extensively in React to describe the structure and appearance of user interfaces.

Here’s an example of JSX code:

const element = 
Hello, world!
;

In this example, we’re creating a new element with the `

` tag and the text “Hello, world!” inside it. This is similar to writing HTML, but we’re doing it directly in our JavaScript code.

JSX is not required when using React, but it is a very convenient and intuitive way to create React elements. When a JSX expression is compiled, it is transformed into a regular JavaScript object called a React element.

Here’s an example of how a JSX expression is compiled:

const element = 
Hello, world!
;

This gets transformed into:

const element = React.createElement("h1", null, "Hello, world!");

The `React.createElement()` function creates a new React element with the specified tag name, properties (or “props”), and children. In this case, the tag name is “h1”, there are no properties, and the child is the string “Hello, world!”.

JSX allows you to use JavaScript expressions inside curly braces, like this:

const name = "John";
const element = 
Hello, {name}!
;

In this example, we’re using the `name` variable inside the curly braces to insert it into the JSX expression.

Overall, JSX is a powerful and convenient way to create React elements, and it makes it easy to write complex UIs in a concise and readable way.